在Android中將縮放放大到圖像查看

Question

我想在我的Android應用中添加縮放。我試過這段代碼，但它只是在圖像中間放大和縮小，我想在整個圖像上應用縮放。

在同一圖像中，我可以在圖像中的某些區域放置一個按鈕嗎？

import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.drawable.Drawable; 
import android.view.KeyEvent; 
import android.view.View; 

public class Zoom extends View { 
    private Drawable image; 
    private int zoomControler=20; 
    public Zoom(Context context) 
    { 
     super(context); 
     image=context.getResources().getDrawable(R.drawable.icon); 
     setFocusable(true); 
    } 

    @Override 
    protected void onDraw(Canvas canvas) { 

     // TODO Auto-generated method stub 
     super.onDraw(canvas); 

     //Here you can control the width and height of the images........ this line is very important 
     image.setBounds((getWidth()/2)-zoomControler, (getHeight()/2)-zoomControler, (getWidth()/2)+zoomControler, (getHeight()/2)+zoomControler); 
     image.draw(canvas); 
    } 

    @Override 
    public boolean onKeyDown(int keyCode, KeyEvent event) { 
     if(keyCode==KeyEvent.KEYCODE_DPAD_UP)// zoom in 
      zoomControler+=10; 
     if(keyCode==KeyEvent.KEYCODE_DPAD_DOWN) // zoom out 
      zoomControler-=10; 
     if(zoomControler<10) 
      zoomControler=10; 

     invalidate(); 
     return true; 
    } 
} 

而這種代碼

import android.app.Activity; 
import android.os.Bundle; 

public class zooming extends Activity { 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle icicle) { 
     super.onCreate(icicle); 
     setContentView(new Zoom(this)); 
    } 
} 

我該如何解決這個問題？

Answer 1

請嘗試下面的代碼。我認爲它會奏效。

import android.app.Activity; 
import android.os.Bundle; 
import android.content.Context; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.graphics.Canvas; 
import android.graphics.Paint; 
import android.graphics.Rect; 
import android.view.Display; 
import android.view.MotionEvent; 
import android.view.View; 
import android.view.WindowManager; 

public class ZoomHelloActivity extends Activity { 

    // Physical display width and height. 
    private static int displayWidth = 0; 
    private static int displayHeight = 0; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

     Display display = ((WindowManager) 
          getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay(); 
     displayWidth = display.getWidth(); 
     displayHeight = display.getHeight(); 
     setContentView(new SampleView(this)); 
    } 

    private static class SampleView extends View { 
     private static Bitmap bmLargeImage; //bitmap large enough to be scrolled 
     private static Rect displayRect = null; //rect we display to 
     private Rect scrollRect = null; //rect we scroll over our bitmap with 
     private int scrollRectX = 0; //current left location of scroll rect 
     private int scrollRectY = 0; //current top location of scroll rect 
     private float scrollByX = 0; //x amount to scroll by 
     private float scrollByY = 0; //y amount to scroll by 
     private float startX = 0; //track x from one ACTION_MOVE to the next 
     private float startY = 0; //track y from one ACTION_MOVE to the next 

     public SampleView(Context context) { 
      super(context); 

      // Destination rect for our main canvas draw. It never changes. 
      displayRect = new Rect(0, 0, displayWidth, displayHeight); 
      // Scroll rect: this will be used to 'scroll around' over the 
      // bitmap in memory. Initialize as above. 
      scrollRect = new Rect(0, 0, displayWidth, displayHeight); 

      // Load a large bitmap into an offscreen area of memory. 
      bmLargeImage = BitmapFactory.decodeResource(getResources(), 
        R.drawable.icon); 
     } 

     @Override 
     public boolean onTouchEvent(MotionEvent event) { 
      switch (event.getAction()) { 
       case MotionEvent.ACTION_DOWN: 
        // Remember our initial down event location. 
        startX = event.getRawX(); 
        startY = event.getRawY(); 
        break; 

       case MotionEvent.ACTION_MOVE: 
        float x = event.getRawX(); 
        float y = event.getRawY(); 
        // Calculate move update. This will happen many times 
        // during the course of a single movement gesture. 
        scrollByX = x - startX; //move update x increment 
        scrollByY = y - startY; //move update y increment 
        startX = x; //reset initial values to latest 
        startY = y; 
        invalidate(); //force a redraw 
        break; 
      } 
      return true; //done with this event so consume it 
     } 

     @Override 
     protected void onDraw(Canvas canvas) { 
      int newScrollRectX = scrollRectX - (int)scrollByX; 
      int newScrollRectY = scrollRectY - (int)scrollByY; 

      // Don't scroll off the left or right edges of the bitmap. 
      if (newScrollRectX < 0) 
       newScrollRectX = 0; 
      else if (newScrollRectX > (bmLargeImage.getWidth() - displayWidth)) 
       newScrollRectX = (bmLargeImage.getWidth() - displayWidth); 

      // Don't scroll off the top or bottom edges of the bitmap. 
      if (newScrollRectY < 0) 
       newScrollRectY = 0; 
      else if (newScrollRectY > (bmLargeImage.getHeight() - displayHeight)) 
       newScrollRectY = (bmLargeImage.getHeight() - displayHeight); 

      // We have our updated scroll rect coordinates, set them and draw. 
      scrollRect.set(newScrollRectX, newScrollRectY, 
       newScrollRectX + displayWidth, newScrollRectY + displayHeight); 
      Paint paint = new Paint(); 
      canvas.drawBitmap(bmLargeImage, scrollRect, displayRect, paint); 

      // Reset current scroll coordinates to reflect the latest updates, 
      // so we can repeat this update process. 
      scrollRectX = newScrollRectX; 
      scrollRectY = newScrollRectY; 
     } 
    }